In the Viewer:
- if I switch between the buttons "No Fit" and "Fit image to window, large only", the image remains on the second setting.
- the "Real Size" button doesn't stay pressed, but selects "No Fit" instead. The resulting zoom level % is remembered when scrolling to other images.
- "Lock zoom" doesn't have any effect, because the zoom is uncorrectly remembered by default.

To reproduce:
1. open Viewer.
2. try the various buttons, expecially scrolling between different images.